Map multiple entities to EF4 abstract base class or interface?

I have multiple tables in a db that are identical in terms of column structure.

I'd like to have this modelled in EF4 so that they all inherit from a single abstract base class, so I can write common methods etc.

I've tried an abstract base class, but this means that I need to add a property to each entity that is NOT in the base class. It also appears I lose my collections, as each one is now a collection of the base type?

I can add partial classes and inherit each from a common interface?

e.g.

Table 1     Table 2     Table 3
Id          Id          Id
Month1开发者_运维问答      Month1      Month1
Month2      Month2      Month2
Month3      Month3      Month3
Quarter2    Quarter2    Quarter2
Quarter3    Quarter3    Quarter3
Quarter4    Quarter4    Quarter4

How can I have a base class or interface called "table" so that I can write all my methods against that and not against each individual table?

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If you are force to keep separate tables, and you just want to be able to write common methods, you can use an Interface and Extension methods like below:

public interface ITableBase{
    int Id{ get; set; }
    // other properties
    void Method1();
    int Method2();
    string Method3(int some_arguments);
}

---

public partial class Table1 : ITableBase{
    // implement ITableBase and other properties and methods
}

---

public partial class Table2 : ITableBase{
    // implement ITableBase and other properties and methods
}

---

public partial class Table2 : ITableBase{
    // implement ITableBase and other properties and methods
}

---

static public class ITableBaseExtensions{
    static public string GetIdAsString(this ITableBase table){
        return table.Id.ToString();
    }
    static public int UsingMethod2(this ITableBase table){
        var i = table.Method2();
        return i * 5 + 9 - 14 / 3 % 7 /* etc... */;
    }
    static public void AddingNewMethodToTables(this ITableBase table, string some_string,
        int some_int, YourType any_other_parameter /* etc... */ ){
        // implement the method you want add to all Table classes
    }
    // 
    // You can add any method you want to add to table classes, here, as an Extension method
    //
}

And in consumers, you can call all methods defined in ITableBaseExtensions class for all tables:

public class MyConsumer{
    public void MyMethod(){
        Table1 t1 = new Table1();
        Table1 t2 = new Table2();
        Table1 t3 = new Table3();

        t1.UsingMethod2(); // will be called from ITableBaseExtensions
        t1.Method2(); // will be called from ITableBase - must implemented in Table1 class

        t2.Method3(some_argument); //  will be called from ITableBase - must implemented in Table2 class
        t2.GetIdAsString(); // will be called from ITableBaseExtensions

        // etc.
    }
}